Originally Posted by jag
This information is inconsistant with what is in the manual. The engine comes stock with a .20mm and .10mm shim (.30mm total) for use with 20-25% nitro. They recommend adding another .10mm shim (.40mm total) for 30%. Where did your information come from?
My information comes from hands on = real experience with Picco engines and Picco based engines. But if you want to be sure, then measure real combustion chamber of your engine and take it from there.
Take all the shims and measure the head button recess and the piston to the top of the liner at top dead center and subtract to determine real combustion chamber without shims. This is the only way to really know. Then add shims accordingly to what I said on my table.
AFM